The ultimate goal is to isolate and measure, by chronometric techniques, the elementary mental processes underlying the management of active memory, and to develop an information processing theory of the mentl structures and control processes based on production systems. Experimental investigations include (i) the role of implicit speech in scanning for presence and scanning for location in active memory (Steinberg), metered memory search, rehearsal, and mental arithmetic in children; (ii) serial position effects in scanning for presence; (iii) memory span and the speed of symbol manipulation in active memory, and (iv) quantification.